When dealing with a large number of ports, one of the performance
bottlenecks is that we loop through all netdevs in the main loop. Miimon
is a contributor to this, executing even if it is not enabled on any
devices.
This patch introduces a counter for the number of netdevs with miimon
configured. If this is 0, then we skip miimon_run() and miimon_wait().
In a test environment of 5000 internal ports and 50 tunnel ports with
bfd, this reduces CPU usage from about 50% to about 45%.
Signed-off-by: Joe Stringer <joestrin...@nicira.com>
---
lib/netdev-linux.c | 26 ++++++++++++++++++++++++--
vswitchd/bridge.c | 2 ++
2 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index 2752623..82e1358 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -61,6 +61,7 @@
#include "netlink.h"
#include "ofpbuf.h"
#include "openflow/openflow.h"
+#include "ovs-atomic.h"
#include "packets.h"
#include "poll-loop.h"
#include "rtnetlink-link.h"
@@ -402,6 +403,11 @@ struct netdev_rx_linux {
* additional log messages. */
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
+/* Polling miimon status for all ports causes performance degradation when
+ * handling a large number of ports. If there are no devices using miimon, then
+ * we skip netdev_linux_miimon_run() and netdev_linux_miimon_wait(). */
+static atomic_int miimon_cnt = ATOMIC_VAR_INIT(0);
+
static void netdev_linux_run(void);
static int netdev_linux_do_ethtool(const char *name, struct ethtool_cmd *,
@@ -490,8 +496,12 @@ netdev_linux_run(void)
{
struct nl_sock *sock;
int error;
+ int miimon;
- netdev_linux_miimon_run();
+ atomic_read(&miimon_cnt, &miimon);
+ if (miimon) {
+ netdev_linux_miimon_run();
+ }
sock = netdev_linux_notify_sock();
if (!sock) {
@@ -552,8 +562,12 @@ static void
netdev_linux_wait(void)
{
struct nl_sock *sock;
+ int miimon;
- netdev_linux_miimon_wait();
+ atomic_read(&miimon_cnt, &miimon);
+ if (miimon) {
+ netdev_linux_miimon_wait();
+ }
sock = netdev_linux_notify_sock();
if (sock) {
nl_sock_wait(sock, POLLIN);
@@ -1222,6 +1236,14 @@ netdev_linux_set_miimon_interval(struct netdev *netdev_,
ovs_mutex_lock(&netdev->mutex);
interval = interval > 0 ? MAX(interval, 100) : 0;
if (netdev->miimon_interval != interval) {
+ int junk;
+
+ if (interval && !netdev->miimon_interval) {
+ atomic_add(&miimon_cnt, 1, &junk);
+ } else if (!interval && netdev->miimon_interval) {
+ atomic_sub(&miimon_cnt, 1, &junk);
+ }
+
netdev->miimon_interval = interval;
timer_set_expired(&netdev->miimon_timer);
}
diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index ec3633c..1e1ef10 100644
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -3470,6 +3470,8 @@ iface_destroy(struct iface *iface)
list_remove(&iface->port_elem);
hmap_remove(&br->iface_by_name, &iface->name_node);
+ /* Ensure that miimon netdevs are counted correctly. */
+ netdev_set_miimon_interval(iface->netdev, 0);
netdev_close(iface->netdev);
free(iface->name);
--
1.7.9.5
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